JPH0258728B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to improvements in combination electrical contacts. Recently, with the development of electrical and electronic technology, various electrical
As electronic devices have become smaller, relays, switches, etc. have also become smaller. However, the relay
As switches and other devices become smaller, the contact gap becomes narrower, making it harder to block arc discharge, making it impossible for the arc to break. Poor withstand voltage and insulation deterioration due to contact wiping become more likely to occur. The contact force and separation force of the electrical contacts become smaller, making it easier for welding to occur. The above problem arises. For this reason, there is a demand for a combination electrical contact that has good arc-blocking properties, welding resistance, and wear resistance, and various combination electrical contacts have been developed, but so far none have been satisfactory. Conventionally, contacts made of Ag alloys or Ag-oxides made by internally oxidizing Ag alloys have been used for combination electrical contacts, and among these, Ag-SnO ₂ contacts and Ag-
A combination electrical contact consisting of SnO ₂ −In ₂ O ₃ −NiO contacts facing each other has superior erosion resistance and durability compared to a combination electrical contact consisting of Ag−Bi ₂ O ₃ contacts facing each other. The welding properties are equally good, but Ag−SnO ₂ contacts and Ag−SnO ₂ −In ₂ O ₃ −
The SnO ₂ in the NiO contact aggregates on the contact surface each time the contact is opened, and since SnO ₂ itself is stable up to around 2000℃, a gentle unevenness is formed on the contact surface, narrowing the contact gap. Over time, the arc interrupting performance deteriorates, and in extreme cases, a situation may arise where the arc cannot be interrupted. In addition, electrical contacts made of Ag-Bi ₂ O ₃ contacts that face each other cannot be welded because Bi has low-temperature sublimation properties and the oxide is brittle and dissociates easily, and Bi has a weak bond with silver. It's hard to do. therefore
It has the same resistance to welding as a combination electrical contact consisting of Ag-SnO ₂ contacts and Ag-SnO ₂ -In ₂ O ₃ -NiO contacts, but the wear is large and uniform. In these combinations of electrical contacts, the contact gap becomes wider in proportion to the number of opening/closing operations, and the arc interrupting performance is improved. However, if the wear is too high, voltage withstand failure and insulation deterioration occur. In this way, conventional combination electrical contacts use the same electrical contact material for the opposing fixed and movable contacts, so they have good wear resistance but poor arc blocking properties, and conversely, arc blocking properties are poor. Although it was good, there were problems such as poor wear resistance. Therefore, the inventor of the present invention has conducted intensive research to develop a combination electrical contact that has good arc interrupting properties, excellent welding resistance, and moderate wear resistance even in miniaturized relays, switches, etc. It has been found that by using different contact materials for the fixed contact and the movable contact, arc blocking performance can be improved without deteriorating welding resistance. The present invention has been made focusing on this point, and uses Ag-Bi ₂ O ₃ contacts and Ag-SnO as a combination electrical contact that can reliably improve arc interrupting properties without deteriorating welding resistance. A combination contact consisting of _two contacts facing each other, and an Ag−
It is an object of the present invention to provide a combination electrical contact formed by opposing Bi ₂ O ₃ and Ag-SnO ₂ -In ₂ O ₃ -NiO contacts. The reason for limiting the materials of the opposing contacts as described above in the combined electrical contact of the present invention is that Ag-
SnO ₂ contacts, Ag−SnO ₂ −In ₂ O ₃ −NiO contacts and Ag
−While taking advantage of the excellent welding resistance of Bi ₂ O ₃ contacts, it also
-The widening of the contact gap due to moderate wear of _{Bi 2} O ₃ contacts takes advantage of the arc-blocking properties, and the synergistic effect of these reduces the welding resistance of conventional electrical contacts made of the same material facing each other. This is to solve the problem of poor arc blocking performance without causing any damage. Also, Ag−SnO ₂ contacts and Ag−SnO ₂ −In ₂ O ₃ −
The reason for limiting the Sn content of NiO contacts to 2 to 15% by weight is that if it is less than 2% by weight, the welding resistance is insufficient, and if it exceeds 15% by weight, there is no problem with the welding resistance, but when the contact is opened and closed, This is because the amount of SnO ₂ that aggregates on the contact surface increases and the contact resistance increases. In addition, the reason for limiting In to 1 to 7% by weight is that if it is less than 1% by weight, it is insufficient to improve the welding resistance, and if it exceeds 7% by weight, In ₂ O ₃ will accumulate on the contact surface when the contact is opened and closed, increasing the contact resistance.
This is because it increases the temperature rise. Then Ag−Bi ₂ O ₃
The reason why the Bi content was limited to 0.5 to 10% by weight is that if it is less than 0.5% by weight, the welding resistance will be insufficient, and if it exceeds 10% by weight, the wear will be extremely high and the life will be shortened. Next, in order to clarify the effects of the combined electrical contact according to the present invention, specific embodiments and conventional examples thereof will be described. (Example 1) An alloy consisting of 0.8% by weight of Bi and the balance being Ag was internally oxidized to form a 5φmm fixed contact made of Ag-Bi ₂ O ₃ , and an alloy consisting of 10% by weight of Sn and the balance being Ag was internally oxidized to form an Ag-Bi 2 O 3 fixed contact. - A 4φmm movable contact made of SnO ₂ was placed facing each other to form an electric contact. (Example 2) An alloy consisting of 0.8% by weight Bi and the balance Ag was internally oxidized to form a fixed contact of 5φmm consisting of Ag-Bi ₂ O ₃ , 6% by weight Sn, 4% by weight In, 0.3% by weight Ni and the balance. By internally oxidizing an alloy consisting of Ag, Ag−
A 4φmm movable contact made of SnO ₂ −In ₂ O ₃ −NiO was placed facing each other to form an electric contact. (Example 3) A 5φmm fixed contact made by internally oxidizing an alloy consisting of 5% Bi by weight and the balance being Ag to contain Ag-Bi ₂ O ₃ , 6% by weight Sn, 4% by weight In, and 0.3% by weight Ni.
Ag by internally oxidizing the alloy consisting of
A 4φmm movable contact made of −SnO ₂ −In ₂ O ₃ −NiO was placed facing each other to form an electric contact. (Example 4) A fixed contact of 5φmm made of Ag-Bi ₂ O ₃ by internally oxidizing an alloy consisting of 5% by weight of Bi and the balance of Ag,
An electric contact was constructed by internally oxidizing an alloy consisting of 10% by weight of Sn and the balance being Ag, and combining it with a 4φmm movable contact made of Ag-SnO ₂ to face each other. (Conventional Example 1) An electrical contact was constructed by internally oxidizing an alloy consisting of 10% by weight of Sn and the balance being Ag, and combining a 5φmm fixed contact made of Ag-SnO ₂ and a 4φmm movable contact facing each other. (Conventional example 2) An electrical contact is constructed by internally oxidizing an alloy consisting of 0.8% Bi and the balance Ag, and combining a 5φmm fixed contact made of Ag-Bi ₂ O ₃ and a 4φmm movable contact facing each other. did. (Conventional example 3) Sn6wt%, In4wt%, Ni0.3wt% and balance
Ag−SnO ₂ is produced by internally oxidizing an alloy consisting of Ag.
−In ₂ O ₃ −NiO 5φmm fixed contact and 4φmm
A movable contact and a movable contact were made to face each other to form a combination electric contact. However, when the welding resistance test, withstand voltage, and arc duration time at interruption were measured for each of these combinations of electrical contacts under the following test conditions, the results shown in the right column of the table below were obtained. * Welding resistance test conditions - AC 100V 50Hz - Supply current 40A, steady current 10A - Switching frequency 20 times/minute - Number of switching cycles 200,000 times * Withstanding voltage - AC 1500V (between contacts) x 1 minute * Arc duration when broken Measurement conditions - DC 24V 3A - Contact gap before test 0.7mm - Breaking speed 5cm/sec

[Table] As is clear from the table above, the contact between Ag-Bi ₂ O ₃ and
A combination contact consisting of Ag-SnO ₂ contacts facing each other, Ag-Bi ₂ O ₃ contacts and Ag-SnO ₂ −In ₂ O ₃ −
The combined electrical contact of the present invention, which is made up of NiO contacts facing each other, has excellent welding resistance equivalent to that of a combined electrical contact made of the same materials facing each other, and has arc-blocking properties compared to conventional examples 1 and 3. It has excellent withstand voltage compared to Conventional Example 2. As detailed above, the combined electrical contact of the present invention has excellent welding resistance, arc interrupting properties, and withstand voltage, so it can suppress the occurrence of welding when used in miniaturized relays, switches, etc. This has the advantage of being able to reliably interrupt the arc.

Claims (1)

[Claims] 1. Ag-SnO ₂ contacts made by internally oxidizing an alloy consisting of 2 to 15% by weight of Sn and the balance being Ag, and Ag-Bi which was made by internally oxidizing an alloy consisting of 0.5 to 10% by weight of Bi and the balance being Ag. A combination electrical contact consisting of ₂ O ₃ contacts facing each other. 2 Sn2~15% by weight, In1~7% by weight, Ni0.01~
Ag-SnO ₂ -In ₂ O ₃ -NiO contact made of internally oxidized alloy consisting of 1% by weight and balance Ag and Bi0.5~10
A combination electrical contact consisting of an internally oxidized Ag-Bi ₂ O ₃ contact made of an alloy consisting of % by weight and the balance being Ag, and facing each other.